Why OpenOffice doesn't have any PPA, no flaptak, no Snap?

[James bond]

These things automate the update/release cycle. For now, a user has to manually do "google search" for update and install the package.

This is an annoying thing to do.
It's very disappointing. Apache other products like Netbeans is available in all from Snapstore to Flathub repository, but not this.

Probably why people depend on LibreOffice so much.

Do something about this. (Else, clear my doubts if I said something wrong.)

[Villeroy]

Because OpenOffice is dead. Every distributor of Linux desktops installs the OpenOffice successor "LibreOffice" which is more actively developed than OpenOffice ever was.

[Zizi64]

OpenOffice 6.4.1 on Ubuntu 19.04 stable Non-LTS release

That is not OpenOffice. There is not such AOO version yet. The 6.x.x is LibreOffice. But the number of the latest Fresh version of the LO is 6.2.3 today.
Or maybe you misspelled the version number: The latest AOO is the v4.1.6 version..

[Villeroy]

Why bother 8 years after the fork? Install Ubuntu and use LibreOffice. It will open all your files and a lot more because it can handle more file formats and it handles most of the foreign file formats better than AOO does. Keep in mind that you have to install the Base component separately when you need it. All serial letters, incl. the ones from spreadsheets, depend on Base. I use the ppa version 6.0 with Ubuntu 18.4. It has some flaws but can do everything I need. In rare cases I resort to another version downloaded from website. AOO on LInux does not work for me because the Base component freezes whenever a certain type of form control gets focus.